Pocketknives commonly include a blade pivotally mounted to a handle, which includes a pocket for receiving the blade to protect a user from being cut by a cutting edge of the blade. When the blade is pivoted to a folded position, the cutting edge lies deep within the pocket of the handle, which allows the pocketknife to be safely and conveniently carried in a shirt pocket or a trouser pocket of a user. A top edge of the blade located opposite the cutting edge remains exposed beyond an aperture of the pocket of the handle when the blade is in the folded position. Blades commonly include a gripping device, such as a fingernail slot or thumbscrew, along the top edge of the blade to facilitate grasping or gripping the blade for extending it from the folded position. A problem with conventional pocketknives is that only a small portion of the blade remains exposed beyond the aperture of the pocket when the blade is in the folded position, making it difficult to grasp or grip the blade for extending it.
Common locking-blade pocketknives include a locking mechanism for automatically locking the blade in place when fully extended for increased safety when the pocketknife is in use, The locking mechanism is manually disengaged by the user by depressing a spring or latch, allowing the blade to be manually pivoted back to the folded position.
One known locking mechanism is a locking liner. In a locking liner, a thin metal liner forms an interior major side surface of the pocket of the handle and includes a spring member biased toward the blade. To prevent the blade from pivoting when in the extended position, an end of the spring member automatically extends behind a heel of the blade to contact the heel of the blade when the blade is fully pivoted to the extended position. A portion of the spring member extends beyond the aperture of the pocket so that the spring member may be manually flexed to disengage it, allowing the blade to be manually pivoted back to the folded position. A problem with locking liners is that the end of the spring member that contacts the heel of the blade has a small surface area that receives heavy wear caused by rubbing against the heel of the blade. With repeated use, this wear can cause the fit of the locking liner to become sloppy, allowing the blade to move slightly in the locked position.